The invention is relating to poly(alkenyl substituted aromatic) and elastomer containing polymer compositions and more particularly to polymer compositions containing polyphenylene ethers or structurally related polymers, poly(alkenyl substituted aromatic) and elastomers, and to their preparation.
A great variety of processes for the preparation of compositions containing a polyphenylene ether resin, an elastomer and a poly(alkenyl aromatic) resin has already been proposed in the past in order to improve the mechanical properties of such polyphenylene ether resin and poly(alkenyl aromatic) resin compositions.
For example U.S. Pat. No. 3,664,977 discloses a resin improved in impact resistance obtained by continuously subjecting to thermic bulk polymerization a mixture composed mainly of an alkenyl aromatic compound (78-85 parts by weight) and containing a rubber substance selected from inter alia crepe rubber, butadiene-styrene copolymer rubber, butadiene-acrylonitrile copolymer rubber, polyisoprene rubber, polybutadiene rubber and ethylene propylene rubber in an amount of 30 to 10 parts by weight, at a temperature of 70.degree.-170.degree. C. and adding to the polymerization mixture a polyphenylene ether in a proportion of 4.0 to 20 per cent by weight based on the total weight of the final polymer at a time of from the stage immediately after formation of a dispersoid of the rubbery polymer to the stage at which the total polymer concentration reached 40% by weight, and continuing the bulk polymerization of the resulting mixture under sufficient stirring at a temperature of 70.degree.-170.degree. C. to complete the polymerization.
From e.g. German patent No. 2,342,119 are known high resistant thermoplastic compositions, which comprise
(a) a polyphenylene ether resin, representing preferably 20 to 80% by weight of composition, and PA1 (b) a rubber modified polystyrene resin, wherein said rubber modified polystyrene represents a polystyrene matrix, wherein a discontinuous phase consisting of styrene homopolymer particles, which are enveloped in a diene rubber membrane, has been regularly dispersed and said particles showing an average size in the range of from about 0.1 to about 0.7 .mu.m, whereas the membrane thickness being not greater than about 1/4 of the average particle diameter and the diene rubber content being from 1 to 10 by weight of the rubber modified polystyrene and more preferably from 3 to 8% by weight. PA1 (a) a polyphenylene oxide resin that is capped with a compound selected from the group of acid halides acid anhydrides and ketenes; and PA1 (b) an alkenyl aromatic resin; PA1 (a) 90-10 parts by weight of an elastomer block copolymer of the type AB, ABA' and/or (AB).sub.n -X, wherein A and A' represent polymerized vinyl aromatic hydrocarbon blocks and B represents hydrogenated and/or non-hydrogenated polymerized conjugated blocks, and wherein X represents the residue of a multifunctional coupling agent and n an integer of at least 3, and PA1 (b) 10-90 parts by weight of an ethylene copolymer having a density d=0.910-0.945 (g/cm.sup.3), consisting of PA1 (a) 100 parts by weight of hydrogenated block copolymer obtained by hydrogenating a block copolymer comprising at least two polymer blocks A composed mainly of a vinyl-substituted aromatic hydrocarbon and at least one polymer block B composed mainly of a conjugated diene, PA1 (b) 11 to 233 parts by weight of a homopolymeric and/or copolymeric polyphenylene ether resin, having a reduced viscosity in a range of from 0.15 to 0.70 as measured at 30.degree. C. in a 0.5 g/dl chloroform solution, PA1 (c) 10 to 500 parts by weight, preferably 100 to 500 parts by weight of a non-aromatic softening agent for rubber, and PA1 (d) 5 to 150 parts by weight of a polyolefin resin and/or polystyrene resin. PA1 (a) 10-90 parts by weight of partially hydrogenated diene-vinyl aromatic diblock copolymer, PA1 (b) 90-10 parts by weight of partially hydrogenated diene-vinyl aromatic polyblock copolymer with at least three blocks. PA1 (a) from 5 to 94% by weight of a polyamide, PA1 (b) from 5 to 94% by weight of a polyphenylene ether, PA1 (c) from 1 to 20% by weight of a partially hydrogenated PQP'-block copolymer, wherein PA1 (a) 10-90% by weight of a polyphenylene ether, PA1 (b) 0-90% by weight of a fluorine-containing olefinic homopolymer or copolymer, the weight percentages of A and B being calculated with respect to the sum of the quantities by weight of A plus B, PA1 (c) 1-80 parts by weight of a vinylaromatic alkyl-(meth)acrylate copolymer, PA1 (d) 1-20 parts by weight of an hydrogenated, block copolymer having one or more blocks derived from conjugated diene units and having one or more blocks derived from vinyl-aromatic units, PA1 (e) 0-200 parts by weight of a styrene homopolymer and/or rubber-modified styrene polymer, and PA1 (f) 0-50 parts by weight of conventional additives, the parts by weight of C, D and E being calculated per 100 parts by weight A and B. PA1 (a) conversion of polyphenylene ether or a structurally related polymer thereof of the formula ##STR1## wherein R.sub.1 and R.sub.4 each may represent hydrogen, halogen, a phenyl group, alkenyl group, alkadienyl group, an aryloxy group, or wherein R.sub.1 and R.sub.4 each may represent an alkyl group or an alkoxy group, each of the latter containing 12 or less carbon atoms and each optionally substituted by halogen, cyano, hydroxy, phenyl or amino, whereas alkyl or alkoxy groups attached to the terminal phenol nucleus of the chain may be substituted by an amino, dialkylamino or a di(alkanoyl) amide group, wherein the alkyl groups each contain 4 or less carbon atoms, wherein R.sub.2 and R.sub.3 each may represent hydrogen, halogen, a phenyl group, alkenyl group, alkadienyl group, aryloxy group or wherein R.sub.2 and R.sub.3 each may represent a primary or secondary alkyl group or alkoxy group as defined for R.sub.1 and R.sub.4, optionally substituted by halogen, cyano, hydroxy, phenyl, and wherein R.sub.1, R.sub.2, R.sub.3 and R.sub.4 may represent different or the same groups in one repeating unit, and n represents an integer having a value of at least 50 and more preferably 100 to 500, with an acid halide, an acid anhydride or ketene, in at least one alkenyl substituted aromatic monomer, the amount of polyphenylene ether or structurally related polymer being in the range of from 5 to 30% by weight and preferably from 10 to 25% by weight, relative to the weight of the complete final composition; PA1 (b) dissolution of at least one ethylene-propylenediene monomer (EPDM) rubber having a specific density in the range of from 0.85 to 0.95, a Mooney viscosity (ML(1+4) 125.degree. C.) in the range of from 30 to 80, an ethylene content in the range of from 50 to 70% by weight, in an amount of from 5 to 20% by weight, and preferably from 7 to 15% by weight, and an optionally partially hydrogenated diblock copolymer A--B, optionally mixed with minor amounts of triblock copolymers A--B--A, wherein A represents a poly(alkenyl aromatic) block and B represents an optionally partially hydrogenated poly conjugated diene block, having a number average molecular weight in the range of from 10,000 to 1,000,000, and showing a glass transition temperature of -20.degree. C. or below, in an amount of from 1 to 5% by weight calculated on the weight of the complete final composition; PA1 (c) prepolymerization of the obtained mixture until a polymerization degree of from 5 to 20% and preferably from 8 to 15%; PA1 (d) suspending the prepolymerized mass into an aqueous medium; PA1 (e) polymerization by thermal initiation or by initiation by means of at least one free radical initiator, optionally in the presence of an expanding agent.
Hereafter, for example U.S. Pat. No. 4,118,348 discloses a specific process for the preparation of a composition comprising rubber, a polyphenylene ether resin and an alkenyl aromatic addition polymer, which comprises using an alkenyl aromatic monomer as a solvent for the oxidative coupling of a phenol to a polyphenylene ether resin and thereafter adding a rubber and polymerizing the mixture to form said blend of rubber, an alkenyl aromatic addition polymer and a polyphenylene ether resin.
The rubber component amount may vary from 1 to 25 parts by weight, the alkenyl aromatic addition polymer from 5 to 95 parts by weight and polyphenylene ether resin from 10 to 90 parts by weight.
U.S. Pat. No. 4,148,843 discloses a process for the preparation of a composition which comprises:
said process comprising forming a mixture of a capped polyphenylene oxide in an alkenyl aromatic monomer and thereafter heating said mixture for a sufficient period of time at an elevated temperature to form said composition.
Although there is indicated in column 3, lines 35-47 that a variety of rubbery impact modifiers may be added in principle to the composition, not any teaching is given to a person skilled in the art to reach final compositions, which show the presently desired characteristics in order to meet the requirements which are posed on modern engineering plastics.
Also from e.g. British patent No. 1,494,759 a process is known for the preparation of a polymer, which comprises polymerizing an alkenyl aromatic compound in the presence of an ethylene/propylene/tercomponent rubber by a two step mass suspension process, the first step of the process comprising a mass polymerization carried out in the presence of oxygen, the pressure in the first step being from 0.05 to 10 atmospheres gauge.
More particularly rubbers are used obtainable by polymerization of from 70 to 30% by weight of ethylene, 30 to 70% by weight of propylene and from 0.5 to 15% by weight, calculated on the total amount of ethylene and propylenes of a diolefin as the tercomponent, such as 5-ethylene norbornene, dicyclopentadiene, 2,2,1-bicycloheptadiene and 1,4-hexadiene, whereas the rubber component is preferably used in an amount of from 1 to 20% by weight and more preferably of from 4 to 15% by weight based on the vinyl aromatic compound and the rubber component.
An improvement to the latter process was disclosed in e.g. British patent No. 1,514,408 indicating that especially the second step of the process is comprising a suspension polymerization carried out in the presence of a very specific group of a peroxy carboxylic acid esters and preferably those formed in situ from a chloroformic acid ester and a hydroperoxide.
From e.g. European patent application No. 0095098 thermoplastic masses are known, based on modified, high impact styrene polymers and polyphenylene ethers, which in addition comprise a combination of
(b.sub.1) 80-99% by weight of ethylene, and PA2 (b.sub.2) 1-20% by weight of a 1-olefin, having at least four carbon atoms. PA2 .alpha.) the blocks P and P' are prepared from vinyl-substituted aromatic monomers and the total fraction of these blocks in the block copolymers is in the range of from 25 to 40% by weight, PA2 .beta.) the number average molecular weight of the block P is at most 8000 and smaller than the number average molecular weight of the block P', PA2 .gamma.) the block Q is prepared from conjugated diene monomers and represents in total from 60 to 75% by weight of the block copolymer, and PA2 .delta.) from 5 to 30% by weight of the double bonds in block Q are not hydrogenated as well as in addition, PA2 (d) from 0 to 50% by weight of a vinyl aromatic polymer.
The teachings of this European patent application are clearly directed on the preparation of polymer blends by mechanical blending e.g. in an extruder, giving rise to a matrix, wherein two phase structure particles have been dispersed.
With reference to the described results in particular in the table on page 17, a person skilled in the art, in charge of the manufacture of polymer blends showing improved characteristics which may meet the present requirements, would certainly not be inclined to concentrate further research on compositions, comprising ethylene/propylene copolymers.
From e.g. European patent application No. 0009638 a process is known for the manufacture of alkenyl aromatic homo- or copolymers by continuous mass polymerization, initiated thermally or by means of free radical initiators, of an alkenyl aromatic compound or a mixture of alkenyl aromatic compounds, optionally in the presence of a nitrile or an ester of acrylic or methacrylic acid and/or a natural or synthetic rubber, with a one-, two- or multistage continuous prepolymerization and subsequent one- two- or multistage continuous main polymerization and final working up, the polymerization mixture being subjected to heat exchanging and uniform static mixing during the main polymerization stage(s). The process is used particularly in the homo- or copolymerization of styrene, especially the copolymerization with alphamethylstyrene optionally in the presence of EPDM (ethylene-propylene-5-ethylidene-norbornene-2) rubber.
E.g. European patent application No. 0209874 discloses a hydrogenated block copolymer composition, showing a compression set (JIS K 6301; 100.degree. C..times.22 hours; and compressibility 25%) of 65% or less as rubber which comprises
These compositions were prepared by the usual compounding techniques, using melt-kneaders such as single-screw, extruders, twin-screw extruders, Banbury mixers, heating rolls and the like.
From e.g. European patent application No. 297,633 a polymer mixture is known, comprising a polyphenylene ether, a polyamide and an agent to improve the impact strength, the latter comprising
The polymer mixture may optionally comprise in addition thereto fillers, reinforcing fibres, flame retardants, stabilizers, dyes and/or pigment(s) and also an agent to improve the compatibility between the polyphenylene ether and the polyamide.
As may be clearly derived from e.g. Japanese patent applications Nos. 63,289,060; 63,289,061; 63,256,650 and 63,251,457, recent research and development efforts were mainly directed to the application of modified block copolymers of a polyalkenyl aromatic (e.g. styrene) and a conjugated diene, optionally further converted by hydrogenation and by linking carboxylic acid radicals or their derivatives in its units, in compositions comprising polyphenylene ether resin and rubber modified poly(alkenyl substituted aromatic) resin, in order to reach the presently required thermal and mechanical properties and combustibility.
It will be appreciated that according to these Japanese patent applications relatively large amounts of expensive modified block copolymers are to be used for obtaining sufficiently interesting properties of the final compositions.
From e.g. European patent application No. 0,298,365 thermoplastic compositions are known, comprising as essential components
In e.g. European patent application No. 0300178 a polymer mixture is disclosed, which comprises
In spite of extensive continuing research and development there still remains a large need for an economically attractive process for the manufacturing of polymer compositions showing the required thermal and mechanical properties and combustibility.